The conventional procedures for cleaning contaminated groundwater usually have involved taking the groundwater out of the ground, passing the water through a cleaning process, the apparatus for which is above ground, and then either discharging the cleaned water into a drain or stream, or injecting the cleaned water back into the ground.
Under the conventional procedures, the rule has been that the whole of the contaminated groundwater has to be taken out of the ground and passed through an above-ground treatment facility.
Such procedures can be extremely costly, and one major element of the cost arises from the requirement simply of handling the large quantities of water.
The invention is aimed at providing a procedure for cleaning groundwater in-situ, ie in which (at least much of) the groundwater does not have to be removed from the ground.
As to the cleaning process itself, a number of procedures have become conventional. When the contaminant is in suspension, it is possible to simply filter the contaminant out of the water. When the contaminant is dissolved, the contaminant can be sorbed onto a suitable material. In both these cases, however, the contaminant remains intact, and the filter or sorber material still contains the contaminant, and must be disposed of as a hazardous waste. It is much preferred, therefore, that the contaminant be broken down, when that is possible, and converted into harmless substances.
It is known that such breakdown of the contaminants can be achieved through inorganic reactions, and it is also known, especially where the contaminant has an organic component, that contaminants may be broken down by a biological reaction. (This term includes a bio-chemical reaction, ie a chemical reaction which is biologically assisted.)
The invention is aimed at providing an especially convenient means of supplying nutrients and other reactive substances into groundwater, for the purpose of promoting such biological reactions, while the groundwater remains in the ground.
In this specification, the term "aquifer" is used in its broad sense to include any body of ground containing water, and through which the water may move, and is not limited only to a body of ground containing a water supply.